1. Field of the Invention
Exemplary aspects of the present invention generally relate to an image forming apparatus using an ink jet method in which ink is ejected from a nozzle to form an image on a recording medium.
2. Description of the Background Art
There is known an image forming apparatus using an inkjet method in which ink is ejected from an opening of a nozzle onto a recording medium such as a sheet of paper to form an image thereon. The nozzle is generally provided to a recording head, which may contain a plurality of such nozzles.
In such an image forming apparatus, when ink is ejected from the nozzle, some ink adheres to the surface (ink discharge surface) on which the opening is formed, clogging the nozzle. In order to remove the ink and prevent such clogging, a wiper blade made of rubber is often used to wipe the ink from the ink discharge surface.
To solve this problem, an ink repellent layer can be provided to the ink discharge surface so as to make it difficult for the ink to remain there, thereby facilitating wiping away of the ink adhering to the ink discharge surface by the blade.
However, although effective, there is a drawback to the above-described approach. That is, as it moves, the blade deforms due to its elasticity, and a portion of the blade gets inside the nozzle from the tip. As the blade continues its wiping motion, a side surface of the blade frictionally contacts the ink repellent layer in the vicinity of the rim of the nozzle, damaging the ink repellent layer.
In particular, if the ink accumulates and hardens (agglutinates) on the ink discharge surface, the wiper blade wipes away the agglutinated product (ink), and then the agglutinated product sticks to the blade. The wiper blade with the agglutinated ink adhering thereto then rubs against the ink repellent layer in the vicinity of the rim of nozzle.
As a result, the agglutinated product acts like an abrasive agent that promotes damage of the ink repellent layer. When such wiping operation is repeatedly performed over time, the ink repellent layer in the vicinity of the rim of the nozzle in the direction in which the blade moves is worn away, thereby forming an area where ink easily adheres.
When an area substantially near the rim of the nozzle includes a portion where ink easily adheres as described above, the ink spreads over the portion where ink easily adheres to the rest of the rim of the nozzle as the ink is ejected from the nozzle and alters the direction in which the ink is ejected, thereby degrading imaging quality.